The universal coupling was designed to be an inexpensive, quick-connecting, sexless coupling. This coupling was used primarily for the transfer of compressed gases such as air, and it has also been used for the transfer of such gaseous substances as steam and of such liquids as water.
The heads of universal couplings interlock with each other, and in general, all sizes of universal couplings from one-quarter of an inch to one inch fit with each other, and all sizes of universal couplings from one and one quarter of an inch to two inches fit with each other. Hence, the name "universal coupling" has been rendered and is known in the art.
The universal coupling may be a dangerous coupling even when it is used as intended and even more so when it is used with steam. Characteristics which can make the universal coupling dangerous in use in general include the twist which is present in formerly coiled and uncoiled-for-use hose conduit segments, which are coupled by the universal coupling, and the torque provided by the passage of fluid through the conduit segments which are coupled by the universal coupling, e.g., compressed air being passed between flexible hose conduit segments, especially when surging therethrough.
From its inception there have been many attempts to make the universal coupling a safer coupling by means of such features as retaining devices as well as by different gaskets. See, Goodall, U.S. Pat. No. 1,914,368 (Jun. 20, 1933). See also, e.g., Allen, U.S. Pat. No. 2,132,506 (Oct. 11, 1938); Kelly, U.S. Pat. No. 2,250,199 (Jul. 22, 1941); Kutina et al., U.S. Pat. No. 3,831,984 (Aug. 27, 1974); Treloar et al., U.S. Pat. No. 4,502,701 (Mar. 5, 1985).
The reason that attempts are made to make the universal coupling a safer coupling by improving its gasket is because the gasket in general provides the holding power of the universal coupling. The universal coupling requires the friction and pressure of the gasket assembly in order to hold its two heads together as is known in the art. See e.g., Dixon Valve and Coupling Co., Chesterton, Md. 21620, Product Bulletin of Feb. 2, 1987 with Universal Coupling Torque Test of a test conducted between May 22, 1986 and Aug. 8, 1986.
Furthermore, because it generally is the combination of friction and pressure of the gasket that keeps the two heads of a universal coupling together, gaskets for universal couplings are typically made to be very hard and stiff. Thus, for the most part, it may well be difficult for one to connect the two heads of such universal couplings.